White screen after activating

A blank white page means PHP stopped with a fatal error and WordPress could not render anything. The error exists, it is just hidden by default.

First, get back in

If wp-admin is also blank, you are not locked out permanently. Rename the theme folder over SFTP, from wp-content/themes/reign-theme to wp-content/themes/reign-theme-off. WordPress cannot find the active theme and falls back to a default one, which restores admin access.

Then see the actual error

Add these to wp-config.php, above the line that says “That’s all, stop editing”:

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );

Reload the page that was blank, then read wp-content/debug.log. The last entry is your cause.

Turn WP_DEBUG back off when you are done. Leaving it on a live site leaks information.

The two causes that account for most of these

PHP version too old

Reign 8 requires PHP 8.0 or newer. On PHP 7.x it fails with a parse error, which presents as a white screen the moment you activate.

Check your version at Tools > Site Health > Info > Server, or in Reign Settings > Tools under System status. If it is below 8.0, raise it in your host’s control panel. Most hosts make this a dropdown.

A parse error naming a file inside reign-theme with “unexpected token” is almost certainly this.

Memory exhausted

An error saying “Allowed memory size of X bytes exhausted” means PHP ran out of memory. Raise it in wp-config.php:

define( 'WP_MEMORY_LIMIT', '256M' );

If that does not take, your host caps it above WordPress and you need to ask them to raise the PHP memory limit.

Community sites need more memory than brochure sites. 256M is a reasonable floor when BuddyPress or BuddyBoss is active.

If it is neither

A plugin conflict. Rename wp-content/plugins to wp-content/plugins-off to disable everything at once. If the site returns, rename it back and disable plugins one at a time until it breaks again.

A corrupted upload. A zip that did not upload cleanly leaves truncated files. Delete the reign-theme folder entirely and upload a fresh copy. Delete rather than overwrite, so partial files do not survive.

An add-on built for an older version. If you run Reign add-ons, disable them and retest. Update the theme and its add-ons in the same sitting, since an add-on built against an older major version can misbehave against a newer one.

Report it

If none of the above explains it, open a ticket with the last 20 lines of debug.log and your System status from Reign Settings > Tools. The log line is the part that matters, so include it verbatim.